1. Field of the Invention
The present invention relates to an improvement of a seat forming a seat surface portion by stretching, within a frame of a frame body, an elastic body made of cloth or braided goods using at least elastic thread as warp or weft.
2. Description of Relevant Art
Conventionally, there has been already proposed a seat forming a seat surface portion by stretching a net-like elastic body within a frame of a frame body (U.S. Pat. No. 5,013,089, U.S. Pat. No. 5,533,789 and Japanese Patent Application Laid-open No.H8-507935).
This seat can be changed in shape differently from a normal seat by forming its seat surface portion of the net-like elastic body, and the seat surface portion can be provided with cushion properties and air permeability. Further, in this seat, a pad member, a spring member and the like which are necessary for forming the seat surface portion of the normal seat can be omitted so that the weight of the seat can be reduced. Furthermore, since the elastic body is thin, the seat can be assembled into shape having high space efficiency.
For stretching the elastic body within the frame of the frame body, in the case of the above-described conventionally proposed seat, the seat surface portion is formed by stretching one sheet of an elastic body having uniform tension within the entire surface of the frame body. However, a soft touch feeling and a fit feeling conforming a body pressure distribution of a person sitting on the seat can not be obtained by stretching the one sheet of elastic body having uniform tension within the entire surface of the frame body. Further, a posture of the person sitting on the seat is not stable and thus, a seat surface portion having excellent sitting feeling can not be formed.
It is an object of the present invention to provide a seat forming a seat surface portion of an elastic body which has excellent sitting feeling and on which a posture of a person sitting on the seat can be stabilized by providing the seat surface portion with a soft touch feeling and a fit feeling conforming a body pressure distribution of the person sitting on the seat.
It is an object of the present invention to provide a seat forming a seat surface portion of an elastic body capable of forming, with a simple structure, the seat surface portion which has excellent sitting feeling and on which a posture of the person sitting on the seat can be stabilized.
According to a first aspect of the present invention, there is provided a seat having a seat surface portion made of an elastic body comprising cloth or braided goods using at least elastic thread as warp or weft, wherein elasticity distribution of the elastic body is changed, and the elastic body is stretched within a frame of a frame body, thereby forming the seat surface portion.
According to a second aspect of the invention, there is a seat having a seat surface portion made of an elastic body, in which a seat surface section from a lower side to an upper side except seat surface sections which positionally correspond to and support shoulder blades of a person sitting on the seat is formed into an elastic surface having tension suitable for supporting the person sitting on the seat, and the seat surface sections which positionally correspond to and support the shoulder blades of the person sitting on the seat are formed into an elastic surface having relatively lower tension.
According to a third aspect of the invention, there is a seat having a seat surface portion made of an elastic body, in which the seat surface portion is formed from two elastic sheets, one of the elastic sheets is made of cloth or braided goods using at least elastic thread as warp or weft which is stretched within the entire surface of the frame of the frame body, and the other of the elastic sheets is made of cloth or braided goods using at least elastic thread as warp or weft which is stretched within the seat surface section from the lower side to the upper side except the seat surface sections which positionally correspond to and support shoulder blades of a person sitting on the seat.